savings plan not applying

Are you seeing that specific EC2 Saving Plan utilization as 0%? This can be validated when you look at the Utilization report under the Saving Plan section in the cost explorer. Use coverage report, under the Saving Plan section to check that your EC2 spend is not covered 100% so that you have EC2 usage to utilize the saving plan. If both are validated and you still have an issue, please log in a support case.

I like to add in this repost as well to ensure we have the same understanding of how saving plans work: https://repost.aws/questions/QUQ45HOe43SPSAiUJtZ-FJhg/saving-plan-showing-as-underused-but-still-being-charged-on-demand-usage